How to Merge Hard Drives on a Mac

by Hollan Johnson

Partitioning a Mac hard drive means to split the hard drive into two or more separate drives. A partitioned hard drive can be handy for running two operating systems on one Mac, like running Mac OS X on one and Windows on another. However, it also means the overall size of both hard drives will be smaller. In order to restore the hard drives to their original singular form you have to merge them together. As long as you have Mac OS X 10.5 or higher you can easily merge hard drives on a Mac.

Step 1

Insert the Mac OS X Install DVD with Disk Utility on it. Restart your Mac and hold down the C key to boot from the disk.

Step 2

Open Disk Utility on the Mac’s desktop.

Step 3

Select the hard drive from the list of drives on the left hand side of the window.

Step 4

Select ‘Partition’ from the tab menu at the top of the window. Click "Current".

Step 5

Choose the hard drive partition you would like to merge with the other hard drive.

Step 6

Click on the minus sign in the lower left hand corner of the window. A new window will open. Press "Delete".

Drag the hard drive partition icon to the full hard drive icon. A new window will open. Press "Yes". The hard drives will be merged into one.


  • Back up both drives before you merge them.
  • If you are merging more than one hard drive, you will have to delete all other drives besides the hard drive you are merging them into.


  • The drive you choose to merge with the other hard drive will have all the information on it deleted before the merge takes place.

Items you will need

  • Mac OS X 10.5 or higher

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